The present invention relates to a semiconductor light-emitting device having a current diffusion layer and method for manufacture thereof.
In recent years, LEDs (Light-Emitting Diodes), which are semiconductor light-emitting devices, have been in the limelight as indoor/outdoor display devices. In particular, with their trend toward higher brightness, the outdoor display market has been rapidly expanding while LEDs have been growing as a medium to replace neon signs. High-brightness LEDs of visible range in such fields have been developed by AlGaInP-based DH (Double Hetero) type LEDs. FIGS. 25A, 25B, 25C show a top view, a sectional view and a functional view, respectively, of a yellow-band AlGaInP-based LED as a semiconductor light-emitting device.
In this semiconductor light-emitting device, as shown in FIGS. 25A and 25B, an n-GaAs buffer layer 301 (thickness: 0.5 xcexcm, Si doping: 5xc3x971017 cmxe2x88x923), an n-AlGaInP cladding layer 302 (thickness: 1.0 xcexcm, Si doping: 5xc3x971017 cmxe2x88x923), an undoped (Al0.3Ga0.7)0.5In0.5P active layer 303 (thickness: 0.6 xcexcm), a p-AlGaInP cladding layer 304 (thickness: 0.7 xcexcm, Zn doping: 5xc3x971017 cmxe2x88x923), a p-AlGaAs current diffusion layer 305 (thickness: 6 xcexcm, Zn doping: 3xc3x971018 cmxe2x88x923), and a p-GaAs cap layer 306 (thickness: 0.1 xcexcm, Zn doping: 3xc3x971018 cmxe2x88x923) are grown on an n-GaAs substrate 310 by MOCVD process, and a first electrode 311 is formed on the substrate side while a second electrode 312 is formed on the grown layer side. Regions of the p-GaAs cap layer 306 other than a device center region thereof opposed to the grown-layer side second electrode 312 have been removed. In this semiconductor light-emitting device, having a pn junction formed within the active layer 303, light emission is generated by recombination of electrons and holes. With this semiconductor light-emitting device molded into 5 mm dia. resin, when a 20 mA current was passed therethrough, the resultant emission intensity was 1.5 cd.
In this semiconductor light-emitting device, as shown in FIG. 25C, a current injected from the grown-layer side second electrode 312 expands within the p-AlGaAs current diffusion layer 305, being injected into the active layer 303, where most part of the current flows to the region under the second electrode 312. As a result, light emission over the region under the second electrode 312 is intercepted by the second electrode 312 so as not to go outside, resulting in an ineffective current. This leads to a problem that the emission intensity would be lower.
Thus, as an solution to this problem, there has been proposed a structure in which a current blocking layer for blocking the current is introduced under the second electrode 312.
FIGS. 26A-26C show a top view, a sectional view and a functional view, respectively, of a semiconductor light-emitting device having the structure in which the current blocking layer is introduced. In this semiconductor light-emitting device, as shown in FIGS. 26A and 26B, an n-GaAs buffer layer 321 (thickness: 0.5 xcexcm, Si doping: 5xc3x971017 cmxe2x88x923), an n-AlGaInP cladding layer 322 (thickness: 1.0 xcexcm, Si doping: 5xc3x971017 cmxe2x88x923), an undoped (Al0.3Ga0.7)0.5In0.5P active layer 323 (thickness: 0.6 xcexcm), a p-AlGaInP cladding layer 324 (thickness: 0.7 xcexcm, Zn doping: 5xc3x971017 cmxe2x88x923), a p-AlGaInP intermediate band gap layer 325 (thickness: 0.15 xcexcm, Zn doping: 2xc3x971018 cmxe2x88x923), a p-GaP first current diffusion layer 326 (thickness: 1.5 xcexcm, Zn doping: 1xc3x971018 cmxe2x88x923), an n-GaP current blocking layer 327 (thickness: 0.4 xcexcm, Si doping: 3xc3x971018 cmxe2x88x923), and a p-GaP second current blocking layer 328 (thickness: 6 xcexcm, Zn doping: 2xc3x971018 cmxe2x88x923) are grown on an n-GaAs substrate 330 by MOCVD process, and a first electrode 331 is formed on the substrate side while a second electrode 332 is formed on the grown layer side.
In this semiconductor light-emitting device, the n-GaP current blocking layer 327 is subjected to etching removal with its device center region left, and the second current diffusion layer 328 is re-grown thereon.
In this semiconductor light-emitting device, as shown in FIG. 26C, a current injected from the grown-layer side second electrode 332, avoiding the n-GaP current blocking layer 327 provided under the second electrode 332, flows to both sides of the n-GaP current blocking layer 327. As a result, as compared with the semiconductor light-emitting device shown in FIG. 25, this semiconductor light-emitting device involves less ineffective current that flows to under the second electrode 332, resulting in increased emission intensity. With this semiconductor light-emitting device applied to a 5 mm dia. molded article, the emission intensity at a 20 mA current conduction was 2.0 cd, an increase of slightly more than 30% as compared with the semiconductor light-emitting device shown in FIG. 25. However, because the thickness of the p-GaP first current diffusion layer 326 provided under the n-GaP current blocking layer 327 is as thick as 1.5 xcexcm, there is still a sneak current going to under the n-GaP current blocking layer 327 as shown in FIG. 26C. Thus, there is a problem that the ineffective current is not eliminated completely.
Accordingly, an object of the present invention is to provide a semiconductor light-emitting device, as well as a method for manufacture thereof, which can be reduced in ineffective current with a simple construction and can effectively take out light to outside.
In order to achieve the above object, there is provided a semiconductor light-emitting device comprising: a first-conductive-type first cladding layer, a first-conductive-type or second-conductive-type or an undoped active layer, a second-conductive-type second cladding layer, a second-conductive-type intermediate band gap layer and a second-conductive-type current diffusion layer, all of which are stacked on one side of a surface of a first-conductive-type semiconductor substrate, a first electrode formed on the other side of the surface of the first-conductive-type semiconductor substrate, and a second electrode formed partly on the second-conductive-type current diffusion layer, wherein
a region of the second-conductive-type intermediate band gap layer just under the second electrode is removed, and the second-conductive-type current diffusion layer is stacked in the removal region on the second-conductive-type second cladding layer, and wherein
a junction plane of the second-conductive-type current diffusion layer and the second-conductive-type second cladding layer has an energy band structure of type II.
With this semiconductor light-emitting device having the above constitution, in the removal region of the second-conductive-type intermediate band gap layer, since the junction plane of the second-conductive-type current diffusion layer and the second-conductive-type second cladding layer becomes high in resistance due to the energy band structure of type II, the current flows to around the removal region, allowing ineffective currents flowing under the second electrode formed partly on the second-conductive-type current diffusion layer to be reduced so that the emission intensity is enhanced. It is noted that the first electrode formed on the other side of the surface of the first-conductive-type semiconductor substrate may be either a partial electrode or a full electrode.
Also, there is provided a semiconductor light-emitting device comprising: a first-conductive-type first cladding layer, a first-conductive-type or second-conductive-type or an undoped active layer, a second-conductive-type second cladding layer, a second-conductive-type intermediate band gap layer and a second-conductive-type current diffusion layer, all of which are stacked on one side of a surface of a first-conductive-type semiconductor substrate, wherein
a device center region of the second-conductive-type intermediate band gap layer is removed, and the second-conductive-type current diffusion layer is stacked in the removal region on the second-conductive-type second cladding layer,
the second-conductive-type current diffusion layer and the second-conductive-type second cladding layer have an energy band structure in which an upper-end position of valence band and a lower-end position of conduction band are in a type II relation, and wherein
the semiconductor light-emitting device further comprises a first electrode formed overall on the other side of the surface of the first-conductive-type semiconductor substrate, and a second electrode formed over the device center region on the second-conductive-type current diffusion layer.
With this semiconductor light-emitting device having the above constitution, in the removal region of the second-conductive-type intermediate band gap layer at the device center region, since the junction plane of the second-conductive-type current diffusion layer and the second-conductive-type second cladding layer becomes high in resistance due to the energy band structure of type II, the current flows to around the removal region, allowing ineffective currents flowing under the second electrode formed at the device center region on the second-conductive-type current diffusion layer to be reduced so that the emission intensity is enhanced.
In one embodiment of the present invention, an upper-side portion of a region of the second-conductive-type second cladding layer corresponding to the removal region of the second-conductive-type intermediate band gap layer is removed.
With the semiconductor light-emitting device of this embodiment, both the removal region at the device center region of the second-conductive-type intermediate band gap layer and the region where the upper-side portion of the second-conductive-type second cladding layer opposed to the removal region has been removed become high in resistance, and besides the high-resistance interface of the second-conductive-type current diffusion layer and the second-conductive-type second cladding layer is near the active layer. Thus, the ineffective currents flowing under the second electrode can further be reduced so that the emission intensity is further enhanced.
Also, there is provided a semiconductor light-emitting device comprising: a first-conductive-type first cladding layer, a first-conductive-type or second-conductive-type or an undoped active layer, a second-conductive-type second cladding layer, a second-conductive-type etching stop layer, a second-conductive-type third cladding layer, a second-conductive-type intermediate band gap layer and a second-conductive-type current diffusion layer, all of which are stacked on one side of a surface of a first-conductive-type semiconductor substrate, wherein
device center regions of the second-conductive-type intermediate band gap layer and the second-conductive-type third cladding layer are removed, respectively, and the second-conductive-type current diffusion layer is stacked in the removal regions on the second-conductive-type etching stop layer,
the second-conductive-type current diffusion layer, the second-conductive-type etching stop layer and the second-conductive-type second cladding layer have an energy band structure in which an upper-end position of valence band and a lower-end position of conduction band are in a type II relation, and wherein
the semiconductor light-emitting device further comprises a first electrode formed overall on the other side of the surface of the first-conductive-type semiconductor substrate, and a second electrode formed over the device center region on the second-conductive-type current diffusion layer.
With the semiconductor light-emitting device having this constitution, the removal regions of the device center region where the second-conductive-type intermediate band gap layer and the second-conductive-type third cladding layer have been removed become high in resistance due to the fact that an energy band structure in which the upper-end position of the valence band and the lower-end position of the conduction band are in the type II relation is formed in the second-conductive-type current diffusion layer, the etching stop layer and the second cladding layer. Besides, the high-resistance interface can be formed near the active layer with high controllability by the presence of the second-conductive-type etching stop layer. Thus, there can be fabricated a semiconductor light-emitting device less in ineffective currents and high in emission intensity with a good yield.
In one embodiment of the present invention, the removal region at the device center region of the second-conductive-type intermediate band gap layer and the second electrode have generally identical configurations and are opposed to each other.
With the semiconductor light-emitting device of this embodiment, the emission efficiency can be optimized by the arrangement that the grown-layer side second electrode and the high-resistance region under the second electrode, both having generally equivalent configurations, are opposed to each other. Thus, the ineffective currents can be lessened and the emission intensity can be enhanced.
Also, there is provided a semiconductor lightemitting device comprising: a first-conductive-type first cladding layer, a first-conductive-type or second-conductive-type or an undoped active layer, a second-conductive-type second cladding layer, a second-conductive-type intermediate band gap layer and a second-conductive-type current diffusion layer, all of which are stacked on one side of a surface of a first-conductive-type semiconductor substrate, wherein
a region of the second-conductive-type intermediate band gap layer other than its device center region is removed, and the second-conductive-type current diffusion layer is stacked in the removal region on the second-conductive-type second cladding layer,
the second-conductive-type current diffusion layer and the second-conductive-type second cladding layer have an energy band structure in which an upper-end position of valence band and a lower-end position of conduction band are in a type II relation, and wherein
the semiconductor light-emitting device further comprises a first electrode formed overall on the other side of the surface of the first-conductive-type semiconductor substrate, and a second electrode formed over the region other than the device center region on the second-conductive-type current diffusion layer.
With the semiconductor light-emitting device having this constitution, at the removal region where the region of the second-conductive-type intermediate band gap layer other than its device center region has been removed, the junction plane of the second-conductive-type current diffusion layer and the second-conductive-type second cladding layer having the energy band structure of the type II becomes high in resistance. Thus, the current flows to the device center region and, as a result, ineffective currents flowing under the second electrode formed over the region other than the device center region on the second-conductive-type current diffusion layer can be reduced, so that the emission intensity is enhanced.
In one embodiment of the present invention, an upper-side portion of the region of the second-conductive-type second cladding layer opposed to the removal region of the second-conductive-type intermediate band gap layer is removed.
With the semiconductor light-emitting device of this embodiment, both the removal region of the second-conductive-type intermediate band gap layer other than its device center region and the region where the upper-side portion of the second-conductive-type second cladding layer opposed to the removal region has been removed become high in resistance, and besides the high-resistance interface of the second-conductive-type current diffusion layer and the second-conductive-type second cladding layer is near the active layer. Thus, the ineffective currents flowing under the second electrode can further be reduced so that the emission intensity is further enhanced.
Also, there is provided a semiconductor light-emitting device comprising: a first-conductive-type first cladding layer, a first-conductive-type or second-conductive-type or an undoped active layer, a second-conductive-type second cladding layer, a second-conductive-type etching stop layer, a second-conductive-type third cladding layer, a second-conductive-type intermediate band gap layer and a second-conductive-type current diffusion layer, all of which are stacked on one side of a surface of a first-conductive-type semiconductor substrate, wherein
regions of the second-conductive-type intermediate band gap layer and the second-conductive-type third cladding layer other than their device center regions are removed, respectively, and the second-conductive-type current diffusion layer is stacked in the removal regions on the second-conductive-type etching stop layer,
the second-conductive-type current diffusion layer, the second-conductive-type etching stop layer and the second-conductive-type second cladding layer have an energy band structure in which an upper-end position of valence band and a lower-end position of conduction band are in a type II relation, and wherein
the semiconductor light-emitting device further comprises a first electrode formed overall on the one side of the surface of the first-conductive-type semiconductor substrate, and a second electrode formed over the region other than the device center region on the second-conductive-type current diffusion layer.
With the semiconductor light-emitting device of this constitution, the removal regions other than the device center regions where the regions of the second-conductive-type intermediate band gap layer and the second-conductive-type third cladding layer have been removed become high in resistance due to the fact that an energy band structure in which the upper-end position of the valence band and the lower-end position of the conduction band are in the type II relation is formed in the second-conductive-type current diffusion layer, etching stop layer and second cladding layer, and besides the high-resistance interface can be formed with high controllability near the active layer by the presence of the second-conductive-type etching stop layer. Thus, there can be fabricated a semiconductor light-emitting device less in ineffective currents and high in emission intensity with a good yield.
In one embodiment of the present invention, a protective layer of the second conductive type is formed on the second-conductive-type intermediate band gap layer.
With the semiconductor light-emitting device of this embodiment, since the second-conductive-type protective layer is present on the second-conductive-type intermediate band gap layer, there is no resistance layer of the interface with the current diffusion layer formed on the second-conductive-type protective layer. Thus, the operating voltage can be lowered.
In one embodiment of the present invention, the first-conductive-type semiconductor substrate is made of GaAs,
the first-conductive-type first cladding layer, the first-conductive-type or second-conductive-type or undoped active layer and the second-conductive-type second cladding layer are made of an AlGaInP-based compound semiconductor that provides lattice matching with GaAs,
the second-conductive-type current diffusion layer is made of a GaP- or AlGaInP-based compound semiconductor, and
the second-conductive-type intermediate band gap layer is made of an AlGaInP-based compound semiconductor.
With the semiconductor light-emitting device of this embodiment, ineffective currents can be reduced so that an AlGaInP-based semiconductor light-emitting device of high emission intensity can be realized.
In one embodiment of the present invention, the first-conductive-type semiconductor substrate is made of GaAs,
the first-conductive-type first cladding layer, the first-conductive-type or second-conductive-type or undoped active layer, the second-conductive-type second cladding layer, the second-conductive-type etching stop layer and the second-conductive-type third cladding layer are made of an AlGaInP-based compound semiconductor that provides lattice matching with GaAs,
the second-conductive-type current diffusion layer is made of a GaP- or AlGaInP-based compound semiconductor, and the second-conductive-type intermediate band gap layer is made of an AlGaInP-based compound semiconductor.
With the semiconductor light-emitting device of this embodiment, ineffective currents can be reduced with a simple construction so that an AlGaInP-based semiconductor light-emitting device of high emission intensity can be realized.
In one embodiment of the present invention, the second-conductive-type intermediate band gap layer made of the AlGaInP-based compound semiconductor has a rate xcex94a/a of lattice matching to GaAs falling within a range of xe2x88x923.2%xe2x89xa6xcex94a/axe2x89xa6xe2x88x922.5%.
With the semiconductor light-emitting device of this embodiment, by the arrangement that the lattice matching rate xcex94a/a of the second-conductive-type intermediate band gap layer to GaAs is set to within a range of xe2x88x923.2%xe2x89xa6xcex94a/axe2x89xa6xe2x88x922.5% in an AlGaInP-based semiconductor light-emitting device, ineffective currents can be reduced and the emission intensity can be enhanced, and besides, the operating voltage can be lowered. Also, lattice defects on the device surface can be lessened and the reliability can be improved.
In one embodiment of the present invention, the second-conductive-type intermediate band gap layer is composed of a plurality of AlGaInP layers having different rates of lattice matching to GaAs, the lattice matching rates xcex94a/a of those AlGaInP layers each falling within a range of xe2x88x923.2xe2x89xa6xcex94a/axe2x89xa6xe2x88x922.5%.
With the semiconductor light-emitting device of this embodiment, the AlGaInP layers composing the second-conductive-type intermediate band gap layer are different from one another in the lattice matching rate and moreover the lattice matching rates xcex94a/a of those AlGaInP layers each fall within a range of xe2x88x923.2xe2x89xa6xcex94a/axe2x89xa6xe2x88x922.5%. As a result, in the AlGaInP-based light-emitting device, ineffective currents can be reduced, by which the emission intensity can be enhanced, and besides the operating voltage can further be lowered and lattice defects on the device surface can be lessened.
In one embodiment of the present invention, a second-conductive-type protective layer made of GaP or an AlGaInP-based compound semiconductor having a Al composition ratio of not more than 20% relative to the total of III group is stacked on the second-conductive-type intermediate band gap layer.
With the semiconductor light-emitting device of this embodiment, since GaP or an AlGaInP protective layer containing less Al is present on the second-conductive-type intermediate band gap layer, there is no resistance layer with the second-conductive-type current diffusion layer formed on the AlGaInP protective layer, so that the operating voltage can be lowered.
In one embodiment of the present invention, the second-conductive-type second cladding layer and the second-conductive-type third cladding layer both made of an AlGaInP-based compound semiconductor have a composition of (AlxGa1xe2x88x92x)0.5In0.5P (where 0.6xe2x89xa6xxe2x89xa61.0).
With the semiconductor light-emitting device of this embodiment, the second-conductive-type second cladding layer and the second-conductive-type third cladding layer each have a composition of (AlxGa1xe2x88x92x)0.5In0.5P (where 0.6xe2x89xa6xxe2x89xa61.0). As a result of this, the operating voltage can be lowered.
In one embodiment of the present invention, the second-conductive-type intermediate band gap layer has a layer thickness of not more than 0.5 xcexcm.
With the semiconductor light-emitting device of this embodiment, the second-conductive-type intermediate band gap layer has a layer thickness of not more than 0.5 xcexcm. As a result of this, the operating voltage can be lowered.
In one embodiment of the present invention, the second-conductive-type intermediate band gap layer has a carrier concentration of not less than 0.5xc3x971018 cmxe2x88x923.
With the semiconductor light-emitting device of this embodiment, the second-conductive-type intermediate band gap layer has a carrier concentration of not less than 0.5xc3x971018 cmxe2x88x923. As a result of this, the operating voltage can be lowered.
Also, there is provided a method for manufacturing a semiconductor light-emitting device, comprising the steps of:
stacking, one by one on one side of a surface of a first-conductive-type semiconductor substrate, a first-conductive-type first cladding layer, a first-conductive-type or second-conductive-type or an undoped active layer, a second-conductive-type second cladding layer, a second-conductive-type intermediate band gap layer and a second-conductive-type protective layer;
removing a device center region of the second-conductive-type protective layer and a device center region of the second-conductive-type intermediate band gap layer, respectively, by etching;
after the removal step of the second-conductive-type protective layer and intermediate band gap layer, stacking a current diffusion layer on the second-conductive-type protective layer and the second-conductive-type second cladding layer to form, in the second-conductive-type current diffusion layer and the second-conductive-type second cladding layer, an energy band structure in which an upper-end position of valence band and a lower-end position of conduction band are in a type II relation;
forming a first electrode overall on the other side of the surface of the first-conductive-type semiconductor substrate; and
forming a second electrode over the device center region on the second-conductive-type current diffusion layer.
With this semiconductor light-emitting device manufacturing method, the removal region where the device center region of the second-conductive-type intermediate band gap layer has been removed becomes high in resistance because an energy band structure in which the upper-end position of the valence band and the lower-end position of the conduction band are in the type II relation is formed in the second-conductive-type current diffusion layer and second cladding layer become high in resistance. Thus, the current flows to around the removal region, so that ineffective currents flowing under the second electrode formed in the device center region on the second-conductive-type current diffusion layer can be reduced, allowing the emission intensity to be enhanced. Therefore, a semiconductor light-emitting device of high emission intensity can be manufactured.
Also, there is provided a method for manufacturing a semiconductor light-emitting device, comprising the steps of:
stacking, one by one on one side of a surface of a first-conductive-type semiconductor substrate, a first-conductive-type first cladding layer, a first-conductive-type or second-conductive-type or an undoped active layer, a second-conductive-type second cladding layer, a second-conductive-type intermediate band gap layer and a second-conductive-type protective layer;
removing a device center region of the second-conductive-type protective layer and a device center region of the second-conductive-type intermediate band gap layer, respectively, by etching, and further removing an upper-side portion of a region of the second-conductive-type second cladding layer corresponding to the removal region by etching;
after the removal step of the second-conductive-type protective layer, intermediate band gap layer and second cladding layer, stacking a second-conductive-type current diffusion layer on the second-conductive-type protective layer and the second-conductive-type second cladding layer to form, in the second-conductive-type current diffusion layer and the second-conductive-type second cladding layer, an energy band structure in which an upper-end position of valence band and a lower-end position of conduction band are in a type II relation;
forming a first electrode overall on the other side of the surface of the first-conductive-type semiconductor substrate; and
forming a second electrode over the device center region on the second-conductive-type current diffusion layer.
With this semiconductor light-emitting device manufacturing method, the removal region where the device center region of the second-conductive-type intermediate band gap layer has been removed becomes high in resistance because an energy band structure in which the upper-end position of the valence band and the lower-end position of the conduction band are in the type II relation is formed in the second-conductive-type current diffusion layer and second cladding layer become high in resistance. Thus, the current flows to around the removal region, so that ineffective currents flowing under the second electrode formed in the device center region on the second-conductive-type current diffusion layer can be reduced, allowing the emission intensity to be enhanced. Therefore, a semiconductor light-emitting device of high emission intensity can be manufactured.
Also, there is provided a method for manufacturing a semiconductor light-emitting device, comprising the steps of:
stacking, one by one on one side of a surface of a first-conductive-type semiconductor substrate, a first-conductive-type first cladding layer, a first-conductive-type or second-conductive-type or an undoped active layer, a second-conductive-type second cladding layer, a second-conductive-type etching stop layer, a second-conductive-type third cladding layer, a second-conductive-type intermediate band gap layer and a second-conductive-type protective layer;
removing device center regions of the second-conductive-type protective layer, the second-conductive-type intermediate band gap layer and the second-conductive-type third cladding layer by etching;
after the removal step of the second-conductive-type protective layer, intermediate band gap layer and third cladding layer, stacking a second-conductive-type current diffusion layer on the second-conductive-type protective layer and the second-conductive-type etching stop layer to form, in the second-conductive-type current diffusion layer, the second-conductive-type etching stop layer and the second-conductive-type second cladding layer, an energy band structure in which an upper-end position of valence band and a lower-end position of conduction band are in a type II relation;
forming a first electrode overall on the other side of the surface of the first-conductive-type semiconductor substrate; and
forming a second electrode over the device center region on the second-conductive-type current diffusion layer.
With this semiconductor light-emitting device manufacturing method, the removal region where the device center region of the second-conductive-type intermediate band gap layer has been removed becomes high in resistance because an energy band structure in which the upper-end position of the valence band and the lower-end position of the conduction band are in the type II relation is formed in the second-conductive-type current diffusion layer, the second-conductive-type eching stop layer and second cladding layer become high in resistance. Thus, the current flows to around the removal region, so that ineffective currents flowing under the second electrode formed in the device center region on the second-conductive-type current diffusion layer can be reduced, allowing the emission intensity to be enhanced. Therefore, a semiconductor light-emitting device of high emission intensity can be manufactured. Besides, the high-resistance interface can be formed with high controllability near the active layer by the presence of the second-conductive-type etching stop layer. Thus, the yield of this semiconductor light-emitting device can be improved.
Also, there is provided a method for manufacturing a semiconductor light-emitting device, comprising the steps of:
stacking, one by one on one side of a surface of a first-conductive-type semiconductor substrate, a first-conductive-type first cladding layer, a first-conductive-type or second-conductive-type or an undoped active layer, a second-conductive-type second cladding layer, a second-conductive-type intermediate band gap layer and a second-conductive-type protective layer;
removing regions of the second-conductive-type protective layer and the second-conductive-type intermediate band gap layer other than their device center regions, respectively, by etching;
after the removal step of the second-conductive-type protective layer and intermediate band gap layer, stacking a second-conductive-type current diffusion layer on the second-conductive-type protective layer and the second-conductive-type second cladding layer to form, in the second-conductive-type current diffusion layer and the second-conductive-type second cladding layer, an energy band structure in which an upper-end position of valence band and a lower-end position of conduction band are in a type II relation;
forming a first electrode overall on the other side of the surface of the first-conductive-type semiconductor substrate; and
forming a second electrode over the region other than the device center region on the second-conductive-type current diffusion layer.
With this semiconductor light-emitting device manufacturing method, the removal region where the region of the second-conductive-type intermediate band gap layer other than its device center region has been removed becomes high in resistance due to the fact that an energy band structure in which the upper-end position of the valence band and the lower-end position of the conduction band are in the type II relation is formed in the second-conductive-type current diffusion layer and second cladding layer. Thus, the current flows to around the device center region and, as a result, ineffective currents flowing under the second electrode formed over the region other than the device center region on the second-conductive-type current diffusion layer can be reduced, so that the emission intensity is enhanced. Therefore, a semiconductor light-emitting device of high emission intensity can be manufactured.
Also, there is provided a method for manufacturing a semiconductor light-emitting device, comprising the steps of:
stacking, one by one on one side of a surface of a first-conductive-type semiconductor substrate, a first-conductive-type first cladding layer, a first-conductive-type or second-conductive-type or an undoped active layer, a second-conductive-type second cladding layer, a second-conductive-type intermediate band gap layer and a second-conductive-type protective layer;
removing regions of the second-conductive-type protective layer and the second-conductive-type intermediate band gap layer other than their device center regions, respectively, by etching, and further removing an upper-side portion of a region of the second-conductive-type second cladding layer corresponding to the removal region by etching;
after the removal step of the second-conductive-type protective layer, intermediate band gap layer and second cladding layer, stacking a second-conductive-type current diffusion layer on the second-conductive-type protective layer and the second-conductive-type second cladding layer to form, in the second-conductive-type current diffusion layer and the second-conductive-type second cladding layer, an energy band structure in which an upper-end position of valence band and a lower-end position of conduction band are in a type II relation;
forming a first electrode overall on the other side of the surface of the first-conductive-type semiconductor substrate; and
forming a second electrode over the region other than the device center region on the second-conductive-type current diffusion layer.
With this semiconductor light-emitting device manufacturing method, the removal region where the region of the second-conductive-type intermediate band gap layer other than its device center region has been removed becomes high in resistance due to the fact that an energy band structure in which the upper-end position of the valence band and the lower-end position of the conduction band are in the type II relation is formed in the second-conductive-type current diffusion layer and second cladding layer. Thus, the current flows to around the device center region and, as a result, ineffective currents flowing under the second electrode formed over the region other than the device center region on the second-conductive-type current diffusion layer can be reduced, so that the emission intensity is enhanced. Therefore, a semiconductor light-emitting device of high emission intensity can be manufactured.
Also, there is provided a method for manufacturing a semiconductor light-emitting device, comprising the steps of:
stacking, one by one on one side of a surface of a first-conductive-type semiconductor substrate, a first-conductive-type first cladding layer, a first-conductive-type or second-conductive-type or an undoped active layer, a second-conductive-type second cladding layer, a second-conductive-type etching stop layer, a second-conductive-type third cladding layer, a second-conductive-type intermediate band gap layer and a second-conductive-type protective layer;
removing regions of the second-conductive-type protective layer, the second-conductive-type intermediate band gap layer and the second-conductive-type third cladding layer other than their device center regions, respectively, by etching;
after the removal step of the second-conductive-type protective layer, intermediate band gap layer and third cladding layer, stacking a second-conductive-type current diffusion layer on the second-conductive-type protective layer and the second-conductive-type etching stop layer to form, in the second-conductive-type current diffusion layer, the second-conductive-type etching stop layer and the second-conductive-type second cladding layer, an energy band structure in which an upper-end position of valence band and a lower-end position of conduction band are in a type II relation;
forming a first electrode overall on the other side of the surface of the first-conductive-type semiconductor substrate; and
forming a second electrode over the region other than the device center region on the second-conductive-type current diffusion layer.
With this semiconductor light-emitting device manufacturing method, the removal region where the region of the second-conductive-type intermediate band gap layer other than its device center region has been removed becomes high in resistance due to the fact that an energy band structure in which the upper-end position of the valence band and the lower-end position of the conduction band are in the type II relation is formed in the second-conductive-type current diffusion layer, the second-conductive-type eching stop layer and second cladding layer. Thus, the current flows to around the device center region and, as a result, ineffective currents flowing under the second electrode formed over the region other than the device center region on the second-conductive-type current diffusion layer can be reduced, so that the emission intensity is enhanced. Therefore, a semiconductor light-emitting device of high emission intensity can be manufactured.